Portable blower apparatuses and dust collector apparatus (or blower/suction apparatuses) have been conventionally known and widely used for blowing off or sucking in fallen leaves or dusts on the ground or the like to clean the place. A relatively small-sized example of hand-held blower apparatuses is disclosed in JP 2014-36939 A, in which the blower apparatus is mounted with a battery and utilizes an electric motor energized by the battery power. This hand-held blower apparatus consumes relatively small electric power and seldom encounters a trouble with heat generation at the control circuit unit which controls the operation of the blower apparatus, and the control circuit unit is disposed at a convenient position within the housing space without employing any particular contrivance for cooling the control circuit unit. A relatively large-sized example of hand-held blower apparatuses is disclosed in JP 2014-511953 A (PCT entry), equivalent to US 2014/0140861 A1, in which a separate battery is piggybacked by means of a harness H for supplying electric power from the battery to an electric motor. This blower apparatus includes a configuration for cooling the control circuit unit, in which an exterior housing 17 and an interior housing 18 are linked by radial rectifier fins 9 to provide cooling air circulation channels 19, and a control circuit unit (electronic board 10) is attached on a support plate 21 that is integral with the exterior housing 17.